Final answer:
A synthetic blend 15W-40 oil is generally more efficient and can lead to better fuel economy compared to conventional 15W-40 oil, making the answer 'True'.
Step-by-step explanation:
When comparing synthetic blend 15W-40 (often referred to as "Syn-blend") oil to conventional 15W-40 oil, it is generally accepted that synthetic blends can offer improvements in fuel economy. The question is whether a "Syn-blend" 15W-40 will yield better fuel economy than a conventional 15W-40. The answer to this is True. Synthetic blend oils are designed to provide some of the benefits of full synthetic oils, including better low and high temperature viscosity performance, protection against oil breakdown, and can lead to improved fuel economy. However, the degree to which fuel economy is improved can vary based on the vehicle, the driving conditions, and other factors. It's also important to follow the vehicle manufacturer's oil specifications for the best results.